I found this out on our rock fence in a pile of stuff we moved from outside my Dad's garage years ago.
It's 20 1/8th inch in diameter, made of cast bronze/ brass ?, weighs about 50#s (without the hinged bar on the back) and the hole is 4 3/8th's inch in diameter.

In this photo, this end appears to be for some sort of lock when it's closed.

This end is broken off, but I would guess it was a hinge for swiveling it open and shut.

Just another view. If you look close just to the left of the hinge pin is a riveted tag. The number is; 36010. This is the only marking on it.

It's 20 1/8th inch in diameter, made of cast bronze/ brass ?, weighs about 50#s (without the hinged bar on the back) and the hole is 4 3/8th's inch in diameter.

In this photo, this end appears to be for some sort of lock when it's closed.

This end is broken off, but I would guess it was a hinge for swiveling it open and shut.

Just another view. If you look close just to the left of the hinge pin is a riveted tag. The number is; 36010. This is the only marking on it.
